Fizzlemizzle Posted January 10, 2010 Share Posted January 10, 2010 I bought this subwoofer about two years ago and tried it in my car and it was not a very good fit so i'm going to give it a try in HT. I've tried messing with a few enclosure calculators but it seems the specs don't have all the values for the fields? Anyway, i'm not sure if I should go ported or sealed but I do have an idea of what I would like it to be like. As close to flat to 20hz or lower with good output and a smooth response curve from 20 to about 80. If anyone could please help me in the right direction I would greatly appreciate it. Thanks. Specs are as follows: Specifications:* Power handling: 500 watts RMS/800 watts max * VCdia: 2-1/2" * Le:1.00 mH * Impedance: 4 ohms * Re: 3.3 ohms * Frequency range: 18 - 800Hz * Fs: 18 Hz * Magnet weight: 150 oz. * SPL: 90 dB 2.83 V/1m, 87 dB1W/1m * Vas: 9.95 cu. ft. * Qms: 3.10 * Qes: .49 * Qts: .42 * Xmax:14mm * Dimensions: A: 15-5/16", B: 14-1/8", C: 6-1/8". Quote Link to comment Share on other sites More sharing options...
brandonnash Posted January 10, 2010 Share Posted January 10, 2010 Those are very nice drivers. Very nice sound, metal cone, and cheap to boot! Only problem is they need a large enclosure, especially if you go ported. For that driver you should look at building a LLT (Large Low Tuned) enclosure. I don't have WinISD up right now, but I can remember modeling somewhere in the 15 cubic foot range with a lower (15 or so hz) tune. Put the right kind of power to it without over extending it and you'll have something that will compare to most commercial subwoofers that cost nearly 10 times as much as the driver. Try downloading that WinISD and see what you can come up with. Half the fun is designing something like this to call your own. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 12, 2010 Author Share Posted January 12, 2010 So i've entered the sub's specifications into winisd and it's telling me that with a 11.365 cubic foot ported enclosure it would be flat from 1000 hertz down to 20 hertz.Down 1db at 19, 2.5db at 17, down 3.5 at 16, down 5db at 15 and down 10db at 13 hertz.Those seem like very good numbers and I'm sure i've entered everything correctly. The outside dimensions of the enclosure it recomends are: 28.85 x 45.26 x 17.91. Those are very odd numbers, I've found that an enclosure with dimensions of 28.5 x 28.5 x 28.5 would have the internal volume of just .025 cubic feet more. My question is would it sound the same as the recomended enclosure or did it give me the odd numbers for a reason? I've never built a sub box and i'm wondering would 3/4" mdf do the job? Would I have to brace a big ported enclosure like this? I ran the figures with a sealed box and although it would be considerably smaller it seems i'd lose a good deal of very low bass for movies and some output. Any help would be very appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 12, 2010 Author Share Posted January 12, 2010 Ok, so I've finally figured out winisd and i don't need an 11.5 cubic foot enclosure. I've decided on something between 8 and 6 for the best balance of size, extension and output. Now my problem is deciding if I want a cube or somethnig more in the dimensions of a cornwall. Seems like the cornwall shape would be better as I could use height instead of sacrificing floor space. Box construction is the thing that has me confused though. Should I use 2 sheets of mdf for the front baffle for better support? The woofer is only something like 20 pounds and it seems like it would be hard to mount it flush. Also, aside from the challenge of bracing it, that takes from the internal volume so I'm wondering if I could do something like use a couple 1" x .75" pieces to connect opposite sides of the box (front panel to back, side to side etc..) of the box? Should I line the interior of the bo with accoustic stuff? Someone please help. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted January 13, 2010 Share Posted January 13, 2010 The larger the enclosure, the shorter the port will be for the same tuning frequency, keeping port area the same. With a 20 pound driver, there won't be any appreciable sag with a single layer front baffle. You can use hardwood dowels or even 2 x 2's to brace opposite sides of the box. The volume displaced by the port as well as any bracing and the driver displacement must be added to your net enclosure volume to get to your construction volume. As you get smaller in net enclosure volume... it becomes increasingly difficult to fit a port with adequate cross sectional area. Sonotube can be used to make ports larger than commercially available, as well as PVC / ABC pipe, however sonotube is the least expensive. A router with a straight cut bit, a flush trimming bit and a circle jig will make construction easier. You can also use sonotube for the enclosure, but it's fashion appeal is less than other enclosure types. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted January 13, 2010 Share Posted January 13, 2010 In answer to your other questions, yes 3/4" MDF is plenty adequate for an enclosure, but I would suggest if you are cutting the panels yourself to do so outdoors as MDF gives off clouds of nasty dust, as well as releasing formaldehyde. Baltic birch plywood is more expensive, but it's a whole lot less dusty to deal with. Large panels need to be adequately braced, the smaller the panel, the less it will deflect. ( stiffness ) Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 13, 2010 Author Share Posted January 13, 2010 Thanks a bunch michael, the external dimensions of 40h x 25w x 22d with 3/4" mdf give me an internal volume of 10.77 so I figured with the displacement from a few braces and the woofer I'd be around or just a hair under 10. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 13, 2010 Author Share Posted January 13, 2010 So i've been hanging out on the AVS forums and now people are saying I should go with a THTsubwoofer design. What the heck is a THT subwoofer? My head is going to explode, I think I may be over analyzing this whole thing.... Quote Link to comment Share on other sites More sharing options...
brandonnash Posted January 13, 2010 Share Posted January 13, 2010 The THT (Tuba Home Theater) is a very good subwoofer. It's nearly flat to 20 hz and has useable output to about 15 hz if you use a good high pass filter. They're not expensive either. The THT will outperform the dayton RF by miles. The only downsides are they are big and they are more difficult to build, yet I've hear they're not that hard to build. The plans are apparently very well written and easy to follow. I'm a big believer in horn subwoofers now since I've heard danley gear and now have a DTS-10. How much are you wanting to spend overall? Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 13, 2010 Author Share Posted January 13, 2010 Thanks brandon, I've had the Dayton 15" HF for almost 2 years just sitting around so that is absolutely what i'm using. Looks like having a 10^3 enclosure built will be about 200 and I'm expecting the amp to be around 150-200. Don't want a behringer though, I only want around 500 watts and the Behringer's are all like 2000. I want a good clean 500 not a cheap 2000.Anyway, let me run these number by you, i'm kind of intermediate in subwoofer knowledge but the figures seem really good so let me know what you think. Using winisd in the 10^3 box (11.6 cubic foot are bigger but that is just too big) with either a 4" x 8.2" circle port or a 4 x 4 x 11.25" square port the figures are: 100w/1m no room gain 107db even from 500 to 30hz with an f3 of 17.4 hz. 15hz is at 101db, 13hz is 96.8db, 12hz is 94 db with 10hz all the way down to 87.9db. I'm not sure how accurate WinIsd is but I could definitely live with those figures. Please let me know if you think those are off or if they are even good for a budget diy sub. Quote Link to comment Share on other sites More sharing options...
brandonnash Posted January 13, 2010 Share Posted January 13, 2010 If you are settled on a 10 cubic foot box then I would try and do an 18 hz tune and bump up the port size to at least 6" diameter circle port. 8" would be better. The reason for going so big on those is to try and tame any port chuffing. With the 8" port it will be non existent. The 6" may be able to be heard on the loudest of tracks, but it will still be ok with normal playing. The 4" ports would have way too much air moving through them. You do have to remember that you're going to need a high pass filter with something like this too. Elemental designs sells one thats $100 and has high pass filtering down to 5 hz. If you wanted an amp with the subsonic filter built in you can go and look at an o-audio bash amp that's 500 watts. It has a subsonic filter that's adjustable right in your range. The reason for the filter is when you get below the port tuning frequency and if it's playing loudly you will bottom out the driver pretty hard. This will keep that from happening. Unless you don't play it loud at all ever then the high pass filter is a necessity not an option. BTW, the behringer amps are great for home use. I have an ep2500 and have had no problems with it at all. Measured distortions with it are inaudible and also have a lower distortion % than most home theater multi channel amps. if you decide on the behringer you will get an honest 2000 watts from it which would be enough to run a second sub off of when you decide to get a second sub. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 13, 2010 Author Share Posted January 13, 2010 Thanks a bunch for all the input brandon, sub probably wont ever be played to the limit but the filter is probably a good idea anyway. Maybe I will give the behringer a look, it seems like quite a few people use them to power their subs. I will look into a larger port but dont they need to usually be longer? I would like to have the port on the driver side but that side will only be 22" deep and 20.5" deep internally. What do you think about the output figures? Do the look good? Quote Link to comment Share on other sites More sharing options...
michael hurd Posted January 14, 2010 Share Posted January 14, 2010 A 4" port is pretty useless even for low output levels, it will start compressing, causing noises and altering the FR as the levels climb. This is a more suitable port for a 15" driver, it's over 7" inside diameter, around 27" in length if I recall, and the inside is flared as well as a flange attatched to it. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted January 14, 2010 Share Posted January 14, 2010 Another picture showing the inside diameter of said port. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 14, 2010 Author Share Posted January 14, 2010 Wow that is a pretty giant port. I just ran the number I got from Winisd through bassbox and the results are absolutely terrible. This has been the longest, most frustrating two nights and I don't even know where to go from here.I never thought designing a ported enclosure for (1) 15" driver could be such a massive ordeal. If someone has a few minutes could they please help me with this? Quote Link to comment Share on other sites More sharing options...
michael hurd Posted January 14, 2010 Share Posted January 14, 2010 Sure, I can have a look at the driver in WinISD..... but it would also help to have some details about your room.... in order to tailor the FR to the room and make an informed decision. Does the room open into other areas of the house, is it sealed ( meaning a door that is able to be closed ), is it main floor, basement or second floor? This all has a bearing on your desired FR. ( anechoic ) The basement will have the lowest losses, as the walls are going to be concrete. This means that you don't have to build a gigantic bottom dweller sub for this area. Tapering off the response and trading it for more output in the midbass area above 30 hz will keep the actual in room FR flatter. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 14, 2010 Author Share Posted January 14, 2010 Thank you so much michael, the is smallish but it does open up to a lot of other rooms. It is on the main floor of a condo It would be very hard to describe with mspainting a sketch. Suffice to say the room open into about as much as it could but there are two full walls and 1/2 wall. Want the parameters or did you find them? Quote Link to comment Share on other sites More sharing options...
michael hurd Posted January 14, 2010 Share Posted January 14, 2010 If this is a condo, I can understand you not wanting to disturb the neighbors. I would concentrate on > 20-25 hz instead of trying to get the most out of the driver. Most plate amplifiers have a high pass filter somewhere in the 18 hz region, as well as being probably space limited, you may want to keep with that in mind. ( taking up less space than a rack mount amp ) I will have a look at the parameters in a bit, it may be tomorrow before I get back to you. Home Depot as well as most lumberyards in general will make cuts for you, some will do precision cutting as long as you buy material from them for a fee that is reasonable. This makes it easier for you to transport, as then you may only have some flush trimming with a router perhaps after gluing it up. Less dusty as well. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 14, 2010 Author Share Posted January 14, 2010 Thanks michael, I made a outline of the floor it will be on with mspaint, I can e-mail it to you if you'd like. Don't know how to put an image on here. I would like a good bit of low bass output because I wont be here forever. Box can be up to 11^3ft (was planning on 10.7) and I figured it to be in the rectangle shape similar to a cornwall (40h x 25w x 22d). Thanks again for helping me, I know you are very well verse in the subwoofer field and I really appreciate your time. Quote Link to comment Share on other sites More sharing options...
Fizzlemizzle Posted January 14, 2010 Author Share Posted January 14, 2010 Got the sketch on photobucket: http://s977.photobucket.com/albums/ae253/Mstrickland1988/?action=view¤t=Condo.jpg&newest=1 Quote Link to comment Share on other sites More sharing options...
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